Troubleshooting
Problem Heating Cooling Cause Correction
No response to
any thermostat
setting
XXMain power off Check fuses
XXDefective control transformer Replace
XXBroken or loose connection Repair
XXDefective thermostat Replace
Unit short
cycles
XXThermostat improperly located Relocate
XXDefective compressor overload Replace
XXHeat anticipator setting Adjust
Blower runs
but compressor
does not
XXDefective compressor overload Replace(if external)
XXDefective compressor contactor Replace
XXDefective lockout relay Replace
XXSupply voltage too low Correct
XXDefective compressor capacitor Replace
XXDefective windings Replace
XXLimit switches open Check cause/Replace
XXSeized compressor “Bump off” with start capacitor/replace
Insufficient ca-
pacity
XXDirty filter Replace/clean
XXBlower RPM too low Correct
XX(1-phase)blower running backward Checking wiring at capacitor
XXLoss of conditioned air due to leaks in ductwork Repair leaks
X Introduction of excessively hot return air Correct
XXIntroduction of excessively low return air Correct
XXLow on refrigerant charge Locate leak, repair and recharge
XXCap/tube strainer or expansion valve is restricted Replace
XXDefective reversing valve See Touch Test Chart
XXThermostat improperly located Relocate
XXUnit undersized Recalculate heat gains/losses
XXInadequate water flow Increase GPM
XXScaling in chiller Clean or replace
X Water too hot Decrease temperature
X Water too cold Increase temperature
High pressure
switch open
X Inadequate GPM Increase
X Water too hot Decrease temperature
X Inadequate air flow Check, clean blower and coil
X Dirty filter Clean/replace
XXOvercharged with refrigerant Decrease charge
XXDefective pressure switch Check replace
High head
pressure
X Trash in chiller Backflush
X Low water flow Increase GPM
XXOvercharged with refrigerant Decrease charge
XXNon-condensibles in system Evacuate and recharge
XXWater too hot Decrease temperature
X Dirty filter Clean/replace
X Inadequate air flow Check, clean blower and coil
Low suction
pressure
XXUndercharged Locate leak, repair and recharge
XXRestricted metering device Repair/replace
X Inadequate air flow Check, clean blower and coil
X Dirty filter Clean/replace
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